Patent GB-783067-A (GB)
Title: Improvements in the production of 1-aminobenzophenone-sulphone-2-carboxylic acids ortheir esters
Filed: 1956-04-05
Abstract: 1 - Aminobenzophenone - sulphone - 2 - carboxylic acids or their esters are made by nitrating a 2-methyl-benzophenone-sulphone, converting the 1-nitro-2-methylbenzophenone-sulphone to the isoxazole, and reacting the latter with (a) water, followed, if desired, by esterification of the resulting carboxylic acid, or with (b) an organic hydroxy compound, to give an ester direct.  The last stage is preferably carried out in acid or alkaline medium. Non-reacting substituents specified are alkyl, halogen, nitro, alkyl sulphonyl.  The nitration step may effect dias well as mono-nitration, and esterification may be by way of the acid chlorides or by way of the isatoic acid anhydrides.  Conversion to the isoxazole may be effected with oleum of 60-65 per cent sulphur trioxide content.  The products dye cellulose acetate, nylon, polyurethanes, and polyesters.  In examples: (1) 2 - methylbenzophenone - sulphone is nitrated using potassium nitrate and sulphuric acid, the 1 - nitro - 2 - methyl - benzophenone - sulphone so obtained is converted to the isoxazole with oleum, and the isoxazole is either (a) heated with caustic soda solution to give 1-aminobenzophenone - sulphone - 2 - carboxylic acid, or (b) heated with potassium cyanide in ethanol to give the carboxylic ester; the ethanol may be replaced by n-butanol; (2) the 1-aminobenzophenone - sulphone - 2 - carboxylic acid obtained under (1) is treated with phosgene in nitrobenzene to give the isatoic acid anhydride which is reacted with ethylene glycol or phenol to give the corresponding esters; (3) the 1-nitro-2-methylbenzophenone-sulphone is further nitrated with nitrating acid and two dinitro bodies separately obtained, converted to the nitroisoxazoles, and these isoxazoles heated with caustic soda solution to obtain the acid.ALSO:1 - Aminobenzophenone - sulphone - 2 - carboxylic acids or their esters are made by nitrating a 2 - methylbenzophenone - sulphone, converting the 1 - nitro - 2 - methylbenzophenonesulphone to the isoxazole, and reacting the latter with (a) water, followed, if desired, by esterification of the resulting carboxylic acid, or with (b) an organic hydroxy compound to give an ester direct.  The last stage is preferably carried out in acid or alkaline medium.  Non-reacting substituents specified are alkyl, halogen, nitro, alkyl sulphonyl. The nitration step may effect dias well as mononitration, and esterification may be by way of the acid chlorides or by way of the isatoic acid anhydrides.  Conversion to the isoxazole may be effected with oleum of 60-65 per cent sulphur trioxide content.  The products dye cellulose acetate, nylon, polyurethanes and polyesters.  In examples: (1) 2-methylbenzophenone-sulphone is nitrated using potassium nitrate and sulphuric acid, the 1-nitro - 2 - methyl - benzophenone - sulphone so obtained is converted to the isoxazole with oleum, and the isoxazole is either (a) heated with caustic soda solution to give 1-aminobenzophenone - sulphone - 2 - carboxylic acid; or (b) heated with potassium cyanide in ethanol to give the carboxylic ester; the ethanol may be replaced by n-butanol; (2) the 1-aminobenzophenone - sulphone - 2 - carboxylic acid obtained under (1) is treated with phosgene in nitrobenzene to give the isatoic acid anhydride which is reacted with ethylene glycol or phenol to give the corresponding esters; (3) the 1-nitro - 2 - methylbenzophenone - sulphone is further nitrated with nitrating acid and two dinitro bodies separately obtained, converted to the nitro-isoxazoles, and these isoxazoles heated with caustic soda solution to obtain the acids.  2 - Methyl - benzophenone - sulphone is prepared by condensation of thio- or dithio-salicylic acid with toluene in concentrated sulphuric acid to form the 2-methylthioxanthone and oxidation of the latter with hydrogen peroxide in acetic acid or a persulphate in sulphuric acid.